1-Chloro-1,2-difluoroethylene (CFCl═CHF; HCFO-1122a) shows promise as a refrigerant with low global-warming potential (GWP) (see PTL 1).
Examples of known methods for producing 1-chloro-1,2-difluoroethylene include a method in which dehalogenation is performed on a halogenated ethane represented by the formula CFClX—CHFX wherein each X represents Cl, Br, or I (a starting material) in the presence of a catalyst, such as zinc; and a method in which 1,2-dichloro-difluoroethylene (CFCl═CFCl) is reduced using a silane compound (see PTL 2 and NPL 1 to 3). However, such methods, due to the use of zinc as a catalyst, must employ batch reaction, which generates a considerable amount of insoluble waste that requires cumbersome treatment, thus resulting in high costs. Additionally, the halogenated ethane used as a starting material, for example, 1,1,2-trichloro-1,2-difluoroethane (CFCl2—CHFCl), is produced by performing F2 addition reaction on trichloroethylene (CCl2═CHCl), and this reaction uses substances that require special care in handling, such as F2 and CoF3.
Another known method for producing 1-chloro-1,2-difluoroethylene dehydrochlorinates 1,2-dichloro-1,2-difluoroethane (CHFCl—CHFCl; HCFC-132) in a liquid phase (see PTL 3 and NPL 4). However, this method uses a considerable amount of a reagent for performing dehydrochlorination, and also generates a considerable amount of chlorides that cannot be recycled for reaction.
Due to these problems in the art, there is demand for a method for efficiently producing 1-chloro-1,2-difluoroethylene at low cost.